92 Sea Ray 5.7 Mercruiser loses power & knocks

greggz

Recruit
Joined
Jul 17, 2010
Messages
1
Just bought this Florida boat two months ago. Apparently owner did not service or take care of it as he claimed. After buying I found out the dip stick was stuck and milky tan oil. Mercruiser cruises at slow speed OK. Good water temp and oil pressure on gauges. When bringing it up to a higher speed, begins to lose power & knocks. Conks out after backing off and then will barely turn over.
I have replaced lifters, replaced carbuerator, got rid of old gas and filters, new impellor pump. Tell me what to check or do next.
 

Alpheus

Lieutenant Commander
Joined
Aug 3, 2009
Messages
1,757
Re: 92 Sea Ray 5.7 Mercruiser loses power & knocks

If its knocking and has been run with milky oil you probably fried the main and rod bearings...
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: 92 Sea Ray 5.7 Mercruiser loses power & knocks

Just bought this Florida boat two months ago. Apparently owner did not service or take care of it as he claimed. After buying I found out the dip stick was stuck and milky tan oil. Mercruiser cruises at slow speed OK. Good water temp and oil pressure on gauges. When bringing it up to a higher speed, begins to lose power & knocks. Conks out after backing off and then will barely turn over.
I have replaced lifters, replaced carbuerator, got rid of old gas and filters, new impellor pump. Tell me what to check or do next.

Well, where do I start......I hate to be the one that say "you should'a" But you should'a water tested the boat before you bought it.

It doesn't appear that you even checked the oil!


Tell me what to check or do next.
My guess is that you'll be replacing the engine. you should probably drain the outdrive and carefully inspect the gear oil. If it's anything like the engine, you might be replacing it too!



Sorry about that,


Rick
 

fossill

Chief Petty Officer
Joined
Jun 20, 2009
Messages
427
Re: 92 Sea Ray 5.7 Mercruiser loses power & knocks

If its knocking and has been run with milky oil you probably fried the main and rod bearings...

Along with the crankshaft.



I'd be pulling the engine and wouldn't even waste my time seeing if it was salvageable.
 
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